I purchased this sword earlier in the year but have known about it for 30 or 40 years.   The man who owned it before me was told this by the man who brought it back from the war.  He was on the Tokyo docks on the day of the Missouri surrender. The surrender party had been disarmed and their swords placed in a pile.  He asked the Americans guarding them what was happening to them.  He was told he could take one which he did.   Movie footage shows some of the Japanese surrender